Hi Joachim

> 2. Pump up the +12V to handle the additional current.

It does not matter whether the 5V supply eats from the total power via a
separate rail or from the +12V rail. 2nd main sentence of
thermodynamcis: "the sum of all energy in a systems stays always the
same". You may be able to change capitalism or the catholic church or
the behaviour of a small synth producer - but you cannot change the laws
of nature ;)

> Btw. if you would use something like the Meanwell T60B or the Taco TXL
> 060-0522TI you could have +5V AND make the power supply cheaper. Then no
> one would complain to pay more for the +5V supply.

The usage of switching power supplies was often discussed in this group.
Final result: it cannot be recommended. For more details please consult
the web-archive of the mail list.

Florian